Motor fuels



Patented Oct. 22,1946

MOTOR FUELS Theodore W. Evans, Oakland, and Alfred G. Cattaneo, Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif., a

corporation of Delaware No Drawing. Application July 31, 1940, Serial No. 348,838

4 Claims.

This invention relates to motor fuels for use in high compression internal combustion spark' ignition engines and relates more particularly to motor fuels blended with an agent which tends to 2 i tion of supercharged spark ignition engines than the latter.

As is known, supercharging is one method of markedly raising the power output of gasoline reduce the knocking of the fuel in supercharged 5 engines. This method comprises boosting the inaso e e nestake pressures to above atmospheric pressure, thus Branched Chain ethers. Such as D- DV increasing the compression pressures. The deet have been suggested as blending agents t gree of supercharging is limited by the knocking raise the octane rating of low octane fuels. Their property of th fuel, for n fuels have a it Primary Value lies in their own high octane compression pressure above which they detonate ings: and by virtue of this Property raise the spontaneously. Obviously the fuel which permits octane rating of the hydrocarbons which are the the highest degree of Supercharging is t t primary source for motor fuels. desirable.

Low octan? fuels have conslfleredthe Response to supercharging may be measured by most susceptible to the beneficlal action of the a unit known as the allowable boost ratio or ethers. Blendmg with hydrocarbon fuels having 3 ratio which is determined as follows: octane ratmgs equal to or greater than those of The intake pressure of an engine running at Eg :5: 3; gggxg gii ggggfifiii i gl ifi constant speed and constant compression ratio is is effected, while the B. t. u. content of the blended figj l fi ggi g g a ggg g Egg; fuel is reduced, it being well known that the B. t. u. r g f 1 t 1711' d d h below those of un on a re erence u e a e same spee an figfiz zgggs ethers a muc compression rat1os,- with var1ed intake pressure until the same degree of knocking is obtained.

We naive now found that blends of The intake pressure of the blended fuel divided ethers w1th hydrocarbons, wh1ch blends possess b the intake ressure of the reference fuel iv octane numbers not substantially greater than p g es e A. B. ratio of the blended fuel. By convention those of the hydrocarbons alone prove vastly the A B ratio i based on sometime a the ref r superior to the straight hydrocarbons insupers 1 s e charged engines. Such blends are obtained when ue mixin certain ethers with hydrocarbons having Examples of fathers Swtable for our mventlon octane ratings equal to or higher than the particare methyl ternary w ether methyl ternary ular ethers. Some few hydrocarbons of lower aimyl ether methyl rtlary heXyl ether, ethyl teroctane than the ethers produce blends which have {nary butyl t n'pmpyl telilary butyl ether, still lower octane number than the hydrocarbons. lsopmpyl ternary butyl ether lsopmpyl ternary Certain asymmetrical dialkyl ethers, one alkyl amyl ther, etc. group of which is a tertiary alkyl radical, prefer- The amounts of the ethers used 1n the blends ably of 4 to 6 carbon atoms such as tertiary butyl are advantageously at least about 5% n preferradical, and the other alkyl group of which cona from 5% to a t u q t t es Outside tains 1 to 3 carbon atoms in a straight or branched these limits y be used if desiredchain, have octane ratings of 100 or slightly lower. n In the table below, examples of blends of hydro- Blends thereof with hydrocarbon fuels of equal carbons with the above ethers are shown, which or higher octane number have octane ratings not blends have equal or lower octane ratings than the higher than those of the hydrocarbon fuel alone, hydrocarbons, but possess materially increased but peculiarly enough permit more efficient opera- A. B. ratios.

Hydrocarbon Blend Ether Percent Name as a.

Methyl tertiary butyl ether- Triptane 1.35 1035 50 10134 1. 45 Do %iso-octane,50%xylene 1.15 97 33% 96% 1.30 Do %iso-octane,20%xylene 1.10 50 99% 1.30 Methyl tertiary amyl'ether.. Isa-octane 1.0 100 50 99 1.20

1 Determined with the aid of iso-octane containing .05 cc. tetra. ethyl lead.

It will be seen that the addition of various quantities of our ethers, while failing to improve the octane rating, markedly increases the allowable boosting of the intake pressure without causing knocking.

Suitable gasoline hydrocarbons with which to blend the ethers are, for example, iso-octane, neohexane, triptane, mixtures of polymer or alkylate gasoline with triptane, mixtures of iso-octane, neohexane, triptane, isopentane, etc., blends of relatively low boiling aromatic hydrocarbons such as toluene, xylenes, ethyl benzene, etc. with high octane aliphatic hydrocarbons, etc.

If desired, anti-detonants such as, tetraethyl lead, aniline, mono methyl aniline, or anti-oxidants such as phenols, aminophenols, may be added to our blended fuels.

We claim as our invention:

1. An improved motor fuel for supercharged spark ignition engines comprising a mixture of methyl, tertiary butyl ether and gasoline hydrocarbons containing a substantial amount of isooctane, said mixture having an octane rating lower than said hydrocarbons, and said fuel having an A. B. ratio greater than that of said gasoline hydrocarbons.

2. An improved motor fuel for supercharged spark ignition engines comprising a mixture of methyl tertiary butyl ether and gasoline hydrocarbons containing a substantial amount of triptane, said mixture having an octane rating lower than said hydrocarbons, and said fuel having an A. B. ratio greater than that of said gasoline hydrocarbons.

3. An improved motor fuel for supercharged spark ignition engines comprising a mixture of methyl tertiary butyl ether and gasoline hydrocarbons containing a substantial amount of neohexane, said mixture having an octane rating lower than said hydrocarbons, and said fuel having an A. B. ratio greater than that of said gasoline hydrocarbons.

4. An improved motor fuel for supercharged spark ignition engines comprising a mixture of methyl tertiary butyl ether and gasoline hydrocarbons containing a substantial amount of hydrocarbons selected from the group consisting of iso-octane, neohexane, triptane, and mixtures thereof.

THEODORE W. EVANS. ALFRED G. CATTANEO. 

